(480c) Chemical Looping Gasification (CLG) of Biomass Using a Novel Bimetallic [Copper-Ferrite] Oxygen Carrier
Chemical looping gasification (CLG) is a new novel technique that utilizes lattice oxygen of metal oxides in place of convention gasification agents like air, steam or pure oxygen to convert carbonaceous fuels into syngas. This method produces high quality syngas free from nitrogen dilution at a low cost. Unlike other traditional gasification technologies, the fuel and air in a CLG process do not mix. Development of an efficient and economic oxygen carrier is essential for the success of a CLG process. The objective of this study was to develop an oxygen carrier with optimum CuO and Fe2O3 composition supported on alumina for CLG and to investigate the use of CuO for the enhancement of an iron based oxygen carrier in biomass CLG. The synergetic properties of Cu-Fe mixed oxides make them a promising material for CLG. While copper has high reactivity, it has issues with agglomeration which is attributed to its low melting point. On the other hand, despite iron oxide being economically cheap and being able to withstand high temperatures, it has slower reactivity. In this work, the bimetallic oxygen carrier was developed using four different methods (Direct Decomposition, Dry Impregnation, Physical Mixing, and combination of Co-precipitation and dry impregnation). The method yielding a carrier with the best TPR-TPO performance (oxygen capacity) was chosen for fixed bed reactions. Biomass chemical looping gasification was investigated in a fixed bed flow reactor with inner diameter of 7 mm using Fe-Cu bimetallic oxide supported on alumina as an oxygen carrier. Fuel conversion was determined to be higher when Fe-Cu oxide was used compared to when only iron oxide was used as the oxygen carrier. Fresh and used oxygen carriers were characterized using SEM-EDS and XRD. The SEM results indicated agglomeration after one cycle of TPR-TPO when only CuO supported on alumina was used in place of a mixture of Fe-Cu oxides. Stability of the oxygen carrier was evaluated after several cycles of oxidation and reduction. It was confirmed that the bimetallic material has a longer lifecycle. XRD results indicated that the products of the bimetallic material reduction was Cu, Fe3O4 and FeO. XRD results also showed that the oxygen carrier can be regenerated to form a crystalline similar to fresh material.